Speaking to World Soccer Magazine, Greenwood said Rashford's recent experiences can help him as he tries to establish himself in United's first-team in the same way.
He said: "He's come through the same pathway as I am following at the club, he's helped me a lot, and it's so good knowing he's done the same.
"He's been in my position and knows how it feels, so it's nice to have someone like that with me and to look up to and play with.
"He's a good lad. We are all proud of him and it's amazing what he's trying to do for people."
Greenwood added: "I think the pathway is really important.
"The pathway is clear to see, you just have to take your chances and go for it."